A recent study focused on plasma samples from preclinical AD patients, determining different proteins and peptides (p-tau 181, amyloid-β40, amyloid-β42), showed some evidence that plasma analysis could guide the selection of candidates to receive a diagnosis of their amyloid status, and so reduce the number of amyloid PET scans required to identify amyloid-β-positive individuals [4]. The gene discussed is MAPT; the disease is Alzheimer disease.